1. Field of the Invention
The present invention relates to STBC (Space-Time Block Coding) transceiving systems combined with LPA (Local Polynomial Approximation)-based beamformer. In particular, the present invention relates to a STBC (Space-Time Block Coding) transceiving system associated with an LPA (Local Polynomial Approximation)-based beamformer, enabling high-speed data transmission by raising a restoration rate and lowering a bit-error rate for a wireless communication signal including many noises by way of forming downlink beams toward a mobile user using multiple array antenna disposed at a base station.
2. Description of the Related Art
Nowadays, while there are increasing demands for advanced wireless communication services, and requirements for higher transmission rates, system performance, and operational efficiencies, it is still not possible to assure high-quality service for users due to various disturbances such as noise, channel fading effects, interference signals, and so forth. Those properties of the wireless communication environment do not ensure that received signal is fully restored over noise signal, so it causes high bit-error rates (BER) for transmission signals. Therefore, it is increasingly necessary to implement wireless communication systems capable of lessening BER by overcoming such inherent properties extant in the wireless environments although noise becomes stronger in proportion to the intensity of signals.
On the other hand, for the purpose of producing high-performance wireless communication systems, there have been various ways proposed to achieve this such as utilizing power control, channel-coding, frequency division, or code division, and employing divided cells or diversity antennas, while there is now interest in smart antennas on downlink.
The smart antenna is configured to form a downlink beam pattern adaptive only to a single mobile user, instead of forming a downlink beam pattern emitting all around from plural array antenna disposed at a base station. This is advantageous as it decreases the interference effect to pluralities of mobile users in a cell and raises the gain of a received signal for the single mobile user.
Meanwhile, if a mobile user is moving, the DOA (direction of arrival) of a signal from the mobile user varies with time. Thus, considering such inherencies of wireless communication environments, there is nothing more important than estimating the DOA of a signal and movement of a user while forming a downlink beam.
However, conventional antenna systems do not consider movements of users, only the current locations of the users. Conventional beam-forming devices operate only considering DOA of a signal from mobile users without information about users' movements. Thus, it is difficult to offer high quality data transmission to moving mobile users. Therefore, the conventional beam-forming systems display good results in estimating DOA of fixed signals, but are unsatisfactory at estimating the movement of mobile users.
Furthermore, studies are still needed to continue improving the system complexity related to calculation amounts and accuracy in estimating movements of mobile users by the beam-forming systems.